Referring to FIG. 1, this is a sectional view showing color cathode ray tube including the fluorescent plate in accordance with conventional art.
The manufacturing process of above fluorescent plate is described as follows.
At first, a photoresist liquid is homogeneously coated onto the surface of a glass panel 1. After the coating of the photoresist liquid, fits a shadow mask 3 with the glass panel 1 and operates an exposure for discriminating red(hereinafter referred to as "R"), green(hereinafter referred to as "G") and blue(hereinafter referred to as "B") fluorescent portions 4.
After the exposure process, one develops a exposed pattern in pure water. After the above processes, one can obtain a pattern of photoresist membrane from which non-exposed portions are eliminated.
After coating the black matrix layer 3 of non-fluorcent absorption material onto the surface of said photoresist layer, unnecessary black matrix layer portions onto the glass panel 1 are removed by hydrofluoric acid, HF solution.
Black matrix layer equivalent to three colors, R, G and B is formed onto the photoresist layer from the etching process.
After the deposition process of the black matrix layer, a deposition process of a fluorescent layer is deposited onto the black matrix layer and the glass panel onto which the black matrix layer is not formed, where the deposited fluorescent layer is discriminated with R, G and B portions. As shown in FIG. 1, each fluorescent portions formed from the above processes has a pattern stretched over black matrix islands.
After the coating process of the fluorescent material, a metallic reflection layer should be deposited onto the surface of the fluorescent layer.
At this time, in order to level the deposited metallic reflection layer, organic film layer is applied onto the fluorescent layer, prior to the metallic layer deposition process.
After that process, an unnecessary organic film layer is removed by thermal decomposition at high temperature of 450.degree. C.
When the organic film is decomposed, various kinds of gases are generated, and the generated gases are exhausted outward through pores in the metallic reflection layer.
Here, a role of the metallic reflection layer 5 is to enhance brightness in the cathode ray tube.
However, in using this conventional processes to fabricate the fluorescent plate, there is a problem that the fluorescent layer is easily not attached on the surface of the black matrix layer because the black matrix layer is composed of small particles having mean diameters of 0.1-0.7 .mu.m, and the surface of the black matrix layer is slippery.
In order to prevent this problem, there has been a method for coating the fluorescent material after deposition of a silica component onto the black matrix.
However, this method also has the problem that the fluorescent layer comes apart.
Moreover, when gases are exhausted during the thermal decomposition of the organic film, in case of effective parts S.sub.e, gases are smoothly exhausted because of pores generated by unevenness of the black matrix surface, but in case of noneffective part S.sub.ne, are not smoothly discharged.
That is, in case of S.sub.ne, gases generated during the thermal decomposition, collide with the attached metallic lower surface, thereby the metallic reflection layer is expanded and partially separated from the surface of the attached black matrix layer. Accordingly, adhesive strength of the metallic layer is decreased, so that the layer is easily separated by bombardment.
The separated metallic layer causes an inner discharge and has a fatal effect on the operation of the cathode ray tube.